//给浮动元素的父级加
.clearfix{
  &:before,
  &:after {
    display:block;
    clear:both;
    content:"";
    visibility:hidden;
    height:0
  }
  &:after {
    clear: both;
  }
}

.flex{
  display: flex;
  justify-content:center;
  align-items:center;
}
.flex-x{
  display: flex;
  align-items:center;
}
.flex-y{
  display: flex;
  justify-content:center;
}
